While looking at cars on wikipedia, I just found out that the brands Peugeot and Citroen are corporate cousins!
But my question is, does that mean that their cars are clones of each other (with styling differences albeit) just as Pontiacs are clones of Chevrolets?
For instance does the C1 = 107, C2 = 207, etc...

Apart from the C1/107(/Toyota Aygo) and the C-Crosser/4007, and commercial vans, not really. They might share platforms and mechanical components, but styling-wise and in other respects they are different. Citroën seem to be reverting to their old characteristic eccentricity while Peugeot, in spite of the huge grinning grilles they now favour, are more conventional.

Well, I know the styling is different, but what I was asking about was the platforms really...

I think they are the same. many Citroens and peugeots are on the same body style with slightly different styling.

You can find platform info on Wikipedia (at least the French one)
Citroën C2/C3 and Peugeot 1007/206/207 share the same platform.

Wikipedia was not paticularly helpful in this instance...

What about the larger ones though? Like the 407, C4, C5, 607, and C6?

407 as same as C5/C6
607 uses same as 605
307/308 has same as C4

C5 is interchangeable with C6? They seem quite different...




What do you mean? They are just two different generations of the same car...

They still used the same platform.
I did not say body, just platform.
If you mean cars using the same body, none of those that I listed are common. Only the C1/107/Aygo have common body parts.