Roman mythology is said to be a carbon copy of Greek and Etruscan beliefs. This is true in many cases, although there are interesting exceptions.
Venus did not begin to be identified with Aphrodite until the 2nd century BCE. Previously, she was the goddess of spring and vegetation. So she resembles the mother goddess worshipped by barbarian agricultural peoples. However, for the Romans, it had an even deeper symbol. Venus gave birth to Aeneas, considered one of the ancestors of the Roman people. So she was the mother from whom the inhabitants of the Eternal City derived their origin.
This was used by Julius Caesar, who declared in public speeches that he came in a straight line from Venus itself. This is another manifestation of his propaganda because such origins seemed to explain his aspirations to power in advance because of his origin, power was to be naturally entitled to him.