In Harry Potter and the Half-Blood Prince, when Professor Slughorn was showing the students the love potion Amortentia, the girls were more affected than the boys. But as per Hermione, it should affect everybody equally. But the girls seemed to be more affected than the boys. Why is that?
Girls seemed more affected by Amortentia
This scene is merely meant to be comical.
While Slughorn is describing the potion, the girls are not more attracted to it, they desire it more than the boys because it is a common joke that teenage girls get crushes easily and want to snag the boy of their dreams.
They approach it because they want a vial to give to the guy they desire the most, in order to force this guy to love them.
Thats a movie thing (I agree... with @TylerShads about the filmmakers trying to be comical) it affects them all equally in the books. Harry mentions smelling a flowery smell and then smelling it again later as Ginny walks up.
It has a different aroma for everyone who smells it, reminding each person of the things that they find most attractive, even if the person themselves doesn't acknowledge or is unaware of their fondness for the object of their affection e.g. Hermione Granger smells fresh cut grass, new parchment, spearmint toothpaste, and Ron Weasley.[1] Harry Potter smelled treacle tart, the woody scent of broomstick handle, and "something flowery that he thought he might have smelled at the Burrow" (which he later realised was the smell of Ginny Weasley's perfume). Ron Weasley smelled his mother's cooking, bacon, and the perfume he gave Hermione in their fifth year at Hogwarts for Christmas.
