European Journal of Cardiovascular Medicine

Human personality and intelligence are intricate traits shaped by the dynamic interplay of genetic, environmental, and sociocultural influences. Among the genetic factors, the ABO blood group system has been a subject of interest not only in clinical medicine but also in psychological and behavioral studies. Traditionally associated with transfusion compatibility and disease susceptibility, blood groups have recently garnered attention for their potential role in influencing personality characteristics and cognitive abilities. Although still a debated topic in scientific circles, the exploration of such associations offers intriguing insights into behavioral genetics.^1-3

In various cultures, especially in East Asian societies like Japan and South Korea, anecdotal beliefs link specific blood groups to distinct personality traits. For instance, individuals with blood group A are often described as calm and responsible, while those with group B are perceived as creative and independent.^3-5 Despite the popularity of these beliefs, empirical evidence remains inconclusive, and limited research has been conducted within the Indian population. Given India’s vast genetic diversity and cultural richness, there is a compelling need to examine whether such associations hold any scientific validity in regional contexts.

Bihar, a state in eastern India with a unique sociocultural landscape, provides a meaningful setting for such investigations. The present study, conducted in the Department of Physiology at Patna Medical College and Hospital, Patna, aimed to evaluate possible correlations between ABO blood groups and personality traits as well as intelligence levels among individuals in this region. By probing these associations, the research seeks to uncover patterns that may contribute to a deeper understanding of how biological factors may intersect with psychological attributes in the Indian demographic.

The findings from this research could have broader implications in the fields of psychology, education, and healthcare. If significant associations are established, they could inform individualized approaches in cognitive training, behavioral therapy, or even career guidance based on inherent personality tendencies. Furthermore, such data could stimulate future multidisciplinary studies and encourage greater integration of genetic markers into psychological assessments, especially in diverse populations like those in Bihar.

Study Design and Setting

This was a cross-sectional observational study conducted in the Department of Physiology, Patna Medical College and Hospital, Patna, Bihar in the period of January 2021 to June 2021. The study aimed to investigate the possible association between ABO blood groups and personality traits as well as intelligence levels among individuals residing in Bihar.

Sample Size and Participants

A total of 120 participants were enrolled for the study using simple random sampling. The study population included healthy individuals aged between 18 and 40 years, who voluntarily consented to participate. Participants were recruited from among students, staff, and attendants visiting Patna Medical College and Hospital. Individuals with known psychiatric or neurological disorders, chronic illnesses, or on medications affecting cognitive or behavioral functioning were excluded to eliminate potential confounding factors.

Ethical Considerations

The study protocol was reviewed and approved by the Institutional Ethics Committee of Patna Medical College and Hospital. Written informed consent was obtained from all participants prior to data collection, and confidentiality of personal information was maintained throughout the study.

Determination of Blood Group

Blood group determination was carried out using standard agglutination methods. A drop of capillary blood was obtained via finger prick and tested with commercially available monoclonal antisera A, B, and D (Rh) on a clean glass slide. The presence or absence of agglutination was used to identify the ABO and Rh blood groups of each participant.

Assessment of Personality Traits

Personality traits were evaluated using a standardized and validated psychometric tool — the Eysenck Personality Questionnaire (EPQ). This tool assesses three major dimensions of personality: extraversion, neuroticism, and psychoticism, along with a lie scale to assess the reliability of responses. Participants were guided on how to complete the questionnaire, and scoring was done as per the standard manual.

Assessment of Intelligence

Intelligence quotient (IQ) was assessed using the Raven’s Progressive Matrices (RPM), a widely accepted non-verbal test of abstract reasoning and general intelligence. It is culture-fair and suitable for assessing individuals from diverse educational and socioeconomic backgrounds. The test consists of visual pattern-based problems arranged in increasing order of difficulty. Scores were computed and interpreted according to the standard scoring scale.

Data Analysis

Data were compiled and statistically analyzed using Microsoft Excel and SPSS software version 25. Descriptive statistics were used to summarize demographic data. Chi-square test and ANOVA were employed to examine associations between blood groups and personality dimensions as well as IQ scores. A p-value of <0.05 was considered statistically significant.

The cross-sectional study conducted at Patna Medical College and Hospital, Patna, Bihar, explored potential associations between ABO blood groups, personality traits (measured using the Eysenck Personality Questionnaire, EPQ), and intelligence levels (assessed via Raven’s Progressive Matrices, RPM) among 120 participants.

Among the 120 participants, 68 were male (56.7%) and 52 were female (43.3%). The majority of participants (41.7%) belonged to the 26–33 age group, followed by 37.5% in the 18–25 age range and 20.8% in the 34–40 age group. Educational attainment varied, with half of the participants being undergraduates, while 25% had education up to high school or below, and 25% held postgraduate or higher qualifications. In terms of occupation, 40% were students, 30% professionals, and 30% fell into the ‘other’ category, which included attendants and visitors. The study included both urban (60%) and rural (40%) residents, ensuring a diverse demographic and socioeconomic representation.

Table 1: Demographic and Socioeconomic Characteristics of Study Participants

Blood group B was found to be the most common among participants, accounting for 33.3% of the sample, followed by group A (26.7%), group O (25.0%), and group AB (15.0%). A large majority of participants (90%) were Rh-positive, while only 10% were Rh-negative. When looking at combined ABO and Rh grouping, B+ was the most prevalent (30.0%), followed by A+ (24.2%) and O+ (22.5%).

Table 2: Distribution of ABO and Rh Blood Groups

The personality trait scores varied slightly across the blood groups. Blood group B had the highest mean score for extraversion (14.2 ± 3.5), while group AB had the lowest (12.8 ± 2.8). Neuroticism scores were highest in group B (12.3 ± 3.1) and lowest in group AB (10.9 ± 2.5). Psychoticism scores were generally consistent across all groups, ranging from 3.9 to 4.5. Scores on the lie scale, used to assess response reliability, showed minimal variation among the groups, ranging from 4.8 to 5.3.

Table 3: Mean Personality Trait Scores by ABO Blood Group

IQ scores were fairly similar across blood groups. The highest mean IQ was observed in group AB (104.2 ± 7.8), while the lowest was in group B (100.8 ± 9.1). The other groups, A and O, had mean IQ scores of 102.4 ± 8.5 and 101.5 ± 8.3 respectively. The IQ range across all groups was between 82 and 120, with overlapping confidence intervals, indicating no substantial differences among groups.

Table 4: Mean IQ Scores by ABO Blood Group

Analysis of variance (ANOVA) revealed no statistically significant differences in any of the personality traits when analyzed across ABO blood groups. The p-values for extraversion (0.30), neuroticism (0.33), psychoticism (0.45), and lie scale (0.52) were all above the threshold of 0.05. Post-hoc analysis using Tukey’s test also did not reveal any significant differences between specific blood group pairs.

Table 5: Statistical Analysis of Personality Traits by ABO Blood Group (ANOVA and Post-Hoc Tests)

Similar to personality traits, the analysis of IQ scores across different blood groups showed no significant differences. The ANOVA yielded a p-value of 0.40, and post-hoc comparisons confirmed that no specific group had a statistically different IQ score compared to others.

Table 6: Statistical Analysis of IQ Scores by ABO Blood Group (ANOVA and Post-Hoc Tests)

Subgroup analyses were conducted to compare personality and IQ scores based on Rh factor and gender within blood groups A and B. No statistically significant differences were observed between Rh-positive and Rh-negative individuals or between male and female participants. For example, extraversion scores in group A were 13.6 ± 3.1 for Rh-positive participants and 13.0 ± 3.5 for Rh-negative participants, with a p-value of 0.78. Similarly, IQ scores in group B were 100.9 ± 9.0 for males and 100.6 ± 9.0 for females, with a p-value of 0.91, indicating no gender-based difference.

Table 7: Subgroup Analysis of Personality Traits and IQ Scores by Rh Factor and Gender

The present study was conducted to explore potential associations between ABO blood groups and psychological attributes—namely, personality traits and intelligence levels—among a population sample from Bihar. While public interest and anecdotal beliefs, especially in countries like Japan and Korea, often suggest a strong link between blood type and behavior or intellect, the findings from this study do not support such associations within the context of an Indian population.

The demographic analysis of the participants revealed a fairly balanced distribution in terms of gender, age, education, and residential background. The largest proportion of participants belonged to the 26–33 age group and held undergraduate-level education. Blood group B emerged as the most prevalent, which is consistent with earlier regional blood group distribution studies conducted in northern India. Rh-positive individuals constituted 90 percent of the sample, reflecting broader national trends.

When personality traits were analyzed across blood groups, there were observable, albeit minor, differences in mean scores. Participants with blood group B had the highest mean scores for extraversion and neuroticism, while those with blood group AB consistently had the lowest scores across most personality dimensions. However, these differences were not statistically significant. The results from ANOVA and post-hoc Tukey tests indicated that no personality trait—extraversion, neuroticism, psychoticism, or lie scale—showed any meaningful variation in relation to ABO blood group. These findings align with a number of previous studies conducted in diverse populations, which also reported weak or non-significant associations between blood type and personality characteristics.^6-8

Similarly, intelligence scores assessed via Raven’s Progressive Matrices did not differ significantly across blood groups. Although group AB recorded the highest mean IQ and group B the lowest, the overlapping confidence intervals and the results of statistical testing suggest these variations are likely due to random distribution rather than any biological linkage. This again echoes the results of previous empirical investigations, which have generally failed to identify a scientifically robust relationship between ABO group and cognitive ability.^5,7

Subgroup analyses further reinforced the absence of significant associations. Neither Rh factor nor gender had any influence on personality trait scores or IQ levels within the blood groups. This uniformity across subgroups highlights the potential universality of psychological development, which seems less likely to be governed by fixed biological markers such as blood type and more by a complex interplay of social, educational, and environmental factors.

It is important to consider the broader implications of these findings. The persistence of blood group stereotypes in popular culture can lead to generalized assumptions and may even contribute to bias in social or occupational settings. Scientific evidence that challenges these assumptions, as provided by this study, can help promote a more individualized and empirically grounded approach to understanding human behavior and intelligence.

That said, certain limitations of the current study must be acknowledged. The sample size, although sufficient for preliminary analysis, may not be large enough to detect subtle associations or rare variations. The study was also confined to a single geographic location within Bihar, which may limit the generalizability of the results to broader populations across India or globally. Additionally, while the EPQ and RPM are well-validated tools, psychological assessment is inherently complex and may benefit from multi-dimensional, longitudinal studies to fully understand trait development over time.

Despite these limitations, the study offers valuable insights by filling a gap in regional literature on the subject. It provides empirical data from an Indian context, where such associations have not been extensively studied, and sets the stage for future investigations with larger and more diverse populations.

The findings from this study suggest that ABO blood groups and Rh factor do not have a significant association with personality traits or intelligence among individuals in Bihar. Psychological traits and cognitive abilities appear to be independent of blood group type in this population. These results encourage a more nuanced understanding of human behavior, one that moves beyond genetic determinism and embraces the multifaceted nature of psychological development.

This study concludes that there is no significant association between ABO blood groups and personality traits or intelligence levels among individuals in Bihar. Despite minor variations in mean scores across different blood groups, statistical analyses revealed no meaningful differences in personality dimensions or IQ. The findings challenge culturally propagated beliefs linking blood type with behavioral or cognitive characteristics, emphasizing instead the complex and multifactorial nature of human psychological development. These results highlight the need to move beyond simplistic genetic explanations and encourage a broader, more integrative approach to understanding personality and intelligence, grounded in scientific evidence. Future studies with larger and more diverse populations across multiple regions are recommended to further validate these findings and explore additional psychosocial and genetic factors that may influence human behavior.

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