Have they gone through any stress during flower? If not...could be problems with the genetics, and should not be used to breed any more.
If they were at all stressed from light leaks, ph drop or fluctuation, too cold...the genetics may be ok, and the plant was using it's survival skills to self-pollinate. That's how we make femmed seeds...but we do it under controlled circumstances, with stable genetics.

If there were no males...all of the seeds will be females. But keep them seperate from your existing seed bank, and when you plant 'em...mark them to be watched for signs of hermaphrodism.
Viable seeds are a darker brown, or a brown with stripes. Lightly tan, yellowish, or white seeds are too young to be viable.
Wait for the trichome heads to turn milky before harvest. Seeds should be done by then...but peel one off to check first, if you are interested in keeping the seeds.