Well.... I will disagree with that theory too..... My hubby was 62 when he had his first son and 64 when he had his second. I just wanted one girl.... just one and I ended up with 3 Boys.... 26 down to 5 and 3. hehe.....Interesting 'age-related' (older rooster) theory. In humans older father is more likely to have a daughter so they say. Here is a study that says older parents (humans) have more daughters
http://www.psychologytoday.com/blog...-are-older-parents-more-likely-have-daughters