A long lost twin?

I was thinking about something similar, that either Mom had an affair and had a child she had to gave up, or their father did (maybe Dad never realized he had fathered a child with a mistress). (Well it probably would have been hard for Mom to keep it a secret from the Dad, unless they had been separated for a while. (Maybe he had to leave for business reasons, or her for an extended European vacation or something.) In either case, Cam's DNA would be a familial match with this (secret) sibling.

But to be fair to the audience, if there really is another sibling,we should be introduced to them soon. It would not be satisfying to have this character show up out of the blue in the final episode or something. But anything is possible!