In my family genetics, we've all been really ill when pregnant with girls. Both my sister & I had terrible M/S through til almost 18weeks pregnant. My mum had M/S through to the same point when she was pregnant with both my sister & I; whereas when she was pregnant with each of my three brothers she only had mild M/S through to the end of the 1st trimester.

Of course, neither my sis or I have had more than one child; and both of us have had girls so we don't have boy pregnancies to compare them to.