I'm taking this cool class on Greek mythology and whenever I Google a God's name, e.g. Aphrodite, there's almost always a 'Roman equivalent', like Venus.

What happened so that the Greeks and Romans ended up worshiping the same gods? I remember reading the Theogony, which is considered to be like the origins of the Greek gods. Did the Greeks send missionaries to convert the Romans? Did the Romans find the Greek texts and adapted them? Do they have completely different origins but only share similarities in terms of their gods?

Thanks for your timê ;)