If you search the forum for "ear crease" you should turn up a number of threads and doctors' comments. If you need help finding the threads let me know and I'll try and help.
First, I don't think that ear creases have anything to do with heart disease at all. I have never heard of any studies that show such an association or connection. The ear crease question has come up on the Dr mediated boards here, and they have always pooh pooh the idea. FWIW, I had a heart attack 2.5 years ago and I don't have ear creases.
On the hand, heart disease does run in your husband's family. It sounds like your husband is off to good start. He doesn't smoke, gets some exercise, eats right, etc. I think he should get check out by a cardiologist and get a cholesterol check. The Drs can decide if a stress test, ekg, calcium measurement are appropiate. They can also tell if heart condition your father in law brother die from is something to worry about or not.