the hair color of her kids is interesting given that both parents are dark haired
not suggesting anything nefarious
its just interesting genetic code
one of them gave their kids strong code from a grandparent
Some people start off as a Towheaded blond toddler, changing into darker hair by the time they seek a date for the Junior Prom. Eye color can change too over time, but more slowly in most cases.
I have brown hair and blue eyes. My wife has darker brown hair and brown eyes. All four of our children have cotton blonde hair and blue eyes.