Thank you DartmoorDoughnut and Kin
Yeah I looked into that too Kin - I saw a post with someone asking about it over a FB group as her partner has only ever had girls and he has a lot of sisters. Everyone was laughing at her about it saying it was just 50:50. But it got me thinking so headed onto Google Scholar and yeah sure enough there appears to be 3 types of men, those who have better XY sperm, those with better XX and those who are about equal. Also other research, did show once you have 2 of the same sex then your chances of having a 3rd the same sex again are dramatically increased and I guess that because your partner is likely to have better sperm of one sex.
Did see some where that it looks like some women are more likely to be successful in carrying one sex over the other. But I never got round to looking into the research for that or where that came from. Mainly because I can't bring myself looking too deeply into reasons behind MCs.