If you do not have dependants of your own,
you are not to claim them.
If you are a single man you cannot claim other people`s kids as your dependant.
This will be a huge red flag for the IRS when you claim them one year and then not the next year.
You have to account for yourself and your own biological dependants.
If you are a single man and have a child with another woman,
you can file your dependent child ONLY if the child has resided with you for more than 80% of the year.
remember this ONLY if the mother does not claim them on her own filings.
Both parents cannot claim the child if they are not married.