They seem a little young to sex. At this age the best way to sex them is to watch their behavior, and that isn't always accurate. If you post pictures again when they are two and a half months to three months old I can probably help. How does that sound? I will watch this thread.
The first picture in the towel looks like a cockerel. They may all be cockerels, but it's a but young to tell. I just got a pair of Silkies and even the breeder wasn't 100% sure on the pullet at four months.