Men' shirts generally have a neck line above the collar bone.
Women's shirts and dresses tend to have a neck line designed to show off the cleavage.
Why is that?
Incidentally, I'm thinking of creating a new law, a bit like Godwin's Law, that states that any internet forum topic that starts off with a generalisation will inevitably lead to someone pretending said generalisation is being quoted as a universal law, just so they can prove how clever they are by pointing out that there are exceptions to that law.
I wonder how far we'll get with this one before someone 'proves me wrong' by pointing out that not all women's tops are low cut.