Maybe not psychology but a fun one in genetics. https://en.m.wikipedia.org/wiki/Fraternal_birth_order_and_male_sexual_orientation https://en.m.wikipedia.org/wi

Maybe not psychology but a fun one in genetics. https://en.m.wikipedia.org/wiki/Fraternal_birth_order_and_male_sexual_orientation https://en.m.wikipedia.org/wiki/Fraternal_birth_order_and_ma...