Why Romans adopted Greek culture, gods?

The Romans did not adopted greek culture and gods; it is assimiliation of the best in its myths and culture.

As much as the proliferation of greek deities being slowly assimiliated into Roman culture from around the 2nd century BCE.

But the Romans also drew on the belief system of the Etruscans, a highly cultured and indigenous people of central Italy who was finally overthrown in the sacking of Veii in 396 BCE.

Roman mythology merged early Italian pastoral gods and their tales from the countryside with the local mythology of places conquered. As long as the people obeyed Roman laws, they were free to practise whatever religion they liked.The Romans also assimiliated the entire Olympic pantheon into their own religious and political system.

The deity who personified Roman majesty,power and fair dealing was Mars and he was venerated throughtout the Roman world as a close second favorite to Jupiter.

Mars evolved from one of the oldest Italian gods, Maris, who originally a spirit of farming and agriculture and an early Etruscan deity and who then merged with the warring attributes of Ares- the Greek god of war.

But the Romans civilized the rough, brainless, berserk nature of Ares to create their imperial Mars.

Thoughtful,protective and self-controlled, he eventually became a well-respected military deity and fathered the twins Romulus and Remus, the founders of Rome.

The Greeks traded and exchanged ideas as well as their wares, many stories were compared, exaggerated, changed and imported from wherever they travelled.

Fascinated by the power of the mind, the Greeks told, retold, wrote down , expanded, annotated and embellished their mythology. The written word ruled supreme.

The Romans did what the Greeks have had done ..... changed and rejuvenated their mythology.

It is not adoption ; it is simply the assimiliation ot the best in greek myth and culture by the Romans.

The answers above give you some of it - the Romans and Greeks were geographically not that far apart, and shared trade links, immigration, etc long before the Romans invaded - which was a long, peicemeal process. So a lot of their myths were already similar. The Romans merged the Greek bits they liked with their own mythology

The Greek actually did this themselves, a great many centuries before, with the tribes and people who lived in those land before them - hence you have Artemis, the virgin huntress, you have many myths relating to sacred twins, a throw back to the Sacred King and his Tanist... pretty much all cultures do this - absorb the mythologist of cultures they invade.

The Romans didn't just do this to the Greeks, either. You've got Roman versions of Greek myths, where Isis keeps popping up, and they were very keen on Mithras. Other myths and deities from other cultures were included, co-opted and changed according to the Roman culture and perception of them.

Why Christians adopted Roman/Greek and Egyptian culture, gods?

Why did the Greeks adopt gods from the cultures before them?

Evolution.

I have a time machine, want to come with to find out?

I don't know, I like the mythology of greek culture though...

The same reasons Americans speak English, they started out as a colony.