Random pea combs on mixed breed chickens

[Chicknladie]

This might be a stupid question but can anyone tell me what might have produced pea combs on my mixed chickens? Rooster is a Lavender Orpington and hens crossed with are as follows;

Several Orpington colors
Silver Laced Wyandotte
Jersey Giant
White Rock
Barred Rock

I’m not understanding why the chicks came out with pea combs (now a year old). I don’t know which hen the eggs came from but 7 out of 10 had pea combs. All had black legs and are solid black with a green sheen.

 

[Willawong Hill]

I would assume the Wyandotte as the others all have single combs.