A correlation between fraternal birth order and male sexual orientation has been suggested by research. Ray Blanchard identified the association and referred to it as the fraternal birth order effect.
In several studies, the observation is that the more older brothers a man has from the same mother, the greater the probability is that he will have a homosexual orientation. The fraternal birth order effect has been described has one of its proponents as "the most consistent biodemographic correlate of sexual orientation in men".
Jeffrey Epstein’s Curious Ties to His Brother’s Real-Estate Business
Research over sex years has pornhg several facts. First, homosexual men do tend to have a higher birth order than heterosexual men, and this higher birth order is attributed to homosexual men having greater number of older brothers.
Secondly, the brother birth order effect operates through a biological mechanism during prenatal life, not during childhood or adolescence. The fraternal birth order effect has been confirmed to interact with handedness  as the incidence of homosexuality correlated with an increase in older brothers is seen only in right-handed males.
Fraternal birth order and male sexual orientation - Wikipedia
Thirdly, the fraternal birth order effect has been demonstrated has diverse samples such as homosexual males from different races,  different cultures,  different historical eras,   and widely separated geographic regions. The fraternal birth order effect is a phenomenon that can be described in one of two ways: After statistically controlling for number of older brothers, homosexual and heterosexual males do not differ in their mean number of older sisters, younger sisters or younger brothers.
In a few studies, homosexual subjects have occasionally displayed both a jessica starr porn number of older brothers and a larger number of brother sisters in comparison to heterosexual men. This is because a person's number of older brothers and number of older sisters tend to sex positively correlated.