INTERESTING topic.
I know a prime example: My Mom.
Do we think it was a mistake? In part. She could be richer today. Well, in fact all our family. And she would have yelled much less througout the last 20 years. That probably means she could be healthier today.
Apart from that...
kids often take after their mother when it comes to brains... this is an unresearached, unbased claim based on personal observations so don't take it seriously. But I've noticed this as a general pattern among people I have met throughout my life. So in terms of the offspring's intellect.. it seems okay if you marry a guy dumber than you are..