Genetic testing and modification during/before pregancy

So, i was having a discussion with my lady, we were talking children in the near future. She has two children currently, but got her tubes tied. Money isnt an issue, but i want a boy, of my own lineage, and it isnt that i wont care for her two, but i want to have a son, or daughter. She did some research to educate herself, and found some interesting stuff. Mainly a fertility clinic can test for autism, and other defects early, and even sex of the baby well before the cutt off for a chemical abortion, IE in the first month. Also this is so early, i believe it would be before she is even impregnated with the little dude/tte. Im all for this, we can choose the sex, and be sure the child wont have crippling diseases or even autism or mental retardation. Also there is the possibility of twins being chosen. Itll be expensive, but if youre going to do it, do it right. So what are the floods thoughts on Genetic modification before or during pregnancy, and not things that are for aesthetics, but that will be a benefit for the child, ie autism, retardation, crippling diseases. So thoughts on having a child genetically chosen and optimized?