Silkies usually have extra toes, feathered legs and a large "poof" of feathers on their head. They always have Black skin and actually have black bones. Comb should be. Black and be a walnut Comb. They can be bearded or non bearded. If they don't have all these characteristics ( black skin, black Comb, feathered feet, extra toes, walnut Comb,) then it's likely they are a cross of something. One of my Silkies I got as a chick seemed bigger than my others. She has black skin, feathered feet a huge "poof" on her head, she's bearded, but as she grew larger than my other Silkies I noticed a red Comb instead of the black. Which leads me to believe she IS crossed with something. I'm thinking it explains her size difference. She's still a beautiful girl and a great bird! Sometimes they sell crosses of Silkies and the smallest clue is the only way you can tell. Something small that is "off " for the Silkie breed like pink skin, red combs, or clean legs. This is just a tip to check if the Silkie is a cross or not. If it is, I wouldn't worry as crosses can make better layers and less broody hens and still be quite beautiful. Hope this helps.