What genetic mechanism explains eyebrow shapes that run in families?

[JeffreyL]

I was looking at some old family photos and noticed how my grandfather, my dad, and I all have this same distinctive eyebrow shape. It got me wondering how a single, seemingly minor trait like that can persist so strongly through generations without any apparent function. What’s actually happening in the DNA that keeps these little quirks faithfully popping up?

[SamuelTJ]

That eyebrow shape feels like a thread tying generations, and DNA is the loom.

[EricFJ]

Most visible traits come from many genes working together with the environment, plus random variation that shows up differently in each person.

[TylerRG]

I used to think it was just grooming passed down, but part of me suspects a few genes quietly doing their own thing.

[MatthewLD]

I am skeptical that a single eyebrow line has a tight DNA script, might be coincidence and shared habits more than biology.

[Emily.L]

Maybe the framing assumes a neat cause and effect, when in fact groups can share a feature because of culture as well as chromosomes.

[NathanD]

Pleiotropy is a concept where one gene in the DNA can influence several features at once, which could explain family likeness without a clear function.