This is the genetics: 9 f: _4 I) {2 ?9 p' e1 Y3 e3 q& Z# A B5 l* Q# R$ Y
XY(man) x XX(woman) = + ?9 F, y0 [" O4 S5 j) \, W
XX or XY, XX or XX, XY or XY. Some people have a twin. ( ^2 {6 ]- Q" q: }, @ [; N* Q( |# A ( \' i& E. r( u* O3 TIf you really need a boy, you can ask a doctor to take your Y only and injiect into your wife's XX, then you will have boy only.' S3 r2 x: A2 R- k6 v
+ N* W) S% X; w/ j8 O& D% i1 u$ tBecareful, eating drug may cause mutation although the possibility is not so high.