Klemperer RosettesTidal transfer of momentum (from the planet to the Sun, and vice versa) would be greater for Mercury than for Venus, so its slow rotation should be slower than Venus, but we see it's the other way. They have similar densities (in order, Earth, Mercury, Venus, Mars), with Mercury a much smaller mass, which suggests that Venus didn't originate in its current orbit, or that Mercury didn't, or both; could also mean (as an online friend pointed out to me) that Venus was walloped but good some while ago, and got turned over from that impact encounter. Mars and Earth have a similar length of day, but Mars' (24 hrs 37 minutes) might be expected to be a great deal slower at formation because of overall lower mass. All this assumes that the model of formation from an accretion disk around the Sun is pretty much correct.
I tend to reject the notion that Venus had anything other than a perfectly boring origin. It has so nearly perfectly circular an orbit that it simply must have accreted in position.
Earth’s early rotational speed, (after the moon-forming collision), was nearly Jovian in speed. It transferred a lot of momentum to the moon, pushing it higher in its orbit. (That particular form of anti-gravity is intriguing, but it seems to only work for large bodies.)
I think this accretion disk hypothesis for the inner planets is promising. The outer planets, like the original Olympian gods, seem to have done things that should not be discussed around women and children.