There are many things you have to look out for:
1. Blue or green eyes. Anything else dooms your sons to lacking Torah – after all, “Einei Talmidei Chachamim C’cholos” (Real Midrash, in Devarim, I think)
2. Naturally straight hair. Will save you thousands over the years in bringing up girls.
3. Ear infections in childhood. Frequent childhood ear infections are correlated with auditory processing disorders, ADHD and autism.
4. Large English vocabulary. Consistent with reading English books in their spare time, and lack of Seforim in the home.
Anyone who doesn’t ask about these, needs to raise their standards, and their havdala candle.