[twigs]

In order for a child to have blonde hair, it must have the gene on both sides of the family in the grandparents' generation.

I've heard this over the years, but it isn't so. All my family is blond (naturally). Both of my brothers married black-eyed and brown-haired wives and both had blond hair and blue-eyed daughters. Both of these daughters now have children who do have brown hair (light), but they had to marry brown-haired men to get them. One of my brothers had a child with an Italian woman and that child had blue eyes too! So, us blondes have heartier genes than all this!

[Paradox]

I've heard this over the years, but it isn't so. All my family is blond (naturally). Both of my brothers married black-eyed and brown-haired wives and both had blond hair and blue-eyed daughters.

My entire family, being hispanic, are dark. Black/Brown hair, dark skin. Two of my sisters married "anglo" men with brown hair.. well lo and behold, each sister has a natural blonde daughter.

However, you CAN have a "blonde" gene and not BE blonde, so it is likely that my family has a blonde gene floating around (I have a great-great grandfather who was from Germany).

[Bon mots]

There are naturally blonde Italians. Not numerous, but plenty of them. My ancestors came from Southern Italy... via Normandy (Normanni - The Normans ruled the Kingdom of the Two Sicilies), and the Normans came out of Scandinavia originally (before Normandy [France])

I had one Aunt, 100% Italian born blonder than Claudia Schiffer. My sister is blonde, and so is my second son.

[Sloth]

I'm not sure you grasp the genetics involved. It is entirely possible for your sisters-in-law's families to have dark coloring and still carry recessive blond-hair/blue-eye genes.