Ok, in my non-majors bio class we just finished our total of two days talking about genetics, etc. According to what we learned, gender of the baby is determined by the man (this I already knew, of course), and each time you concieve there is a brand new 50/50 chance for a boy or a girl. So, the question is, why do certain genders seem more common is some families? For instance:
[ul][li]My maternal grandfather had one sister and two brothers.[/li][li]My mother had three brothers, no sisters, and all male (first) cousins (at least on her father’s side).[/li][li]I have four brothers, no sisters, and all male (first) cousins (all are on my mother’s side, my father was an only child).[/ul][/li]Is this simply coincidence, or is there some biological factor that is causing all of the men in my family to have sons?