Little Arto and Pasha are part of that couple's natural genetics as well esther.

On the bigheads image, Pierone and Decimal are side by side which means the kids will likely either turn out looking like one of them, or one head above or below them. Dono & Saul are above the father, Arto is below the father, Pasha is below the mother and Lilila is above the mother.

That really is a cute family though!