It’s more or less common knowledge that actual hearts aren’t shaped the way we see them in cartoons. It is unclear as to where the modern symbol of the heart truly came from, but here are a few ideas.
1. Some people believe that the heart shape comes from the seedpod of the silphium plant. The plant of which was used as a form of birth control. The seedpod closely resembles what a modern day heart symbol looks like, and since it was used as birth control, people started to associate the symbol with sex and love.
2. Some people also believe that the symbol is simply a bad attempt at drawing a real heart. It is an organ with three chambers, a round top, and a bottom that is pointy. These drawings could have spread through medieval imagery, later to be associated with Valentines day in the 17th century.