... we don't know.
It isn't confirmed, so it's not canon. It's speculation amongst some fans - some think it theorectically possible, others think it's ridiculous.
Points to consider;
1. His surname - just because his surname is Hatake, doesn't mean he's not decended from a MATERNAL Senju line. example: Tobirama has a daughter who marries 'Hatake-san', they have a son called Sakumo Hatake who marries and has a son called KAKASHI.
2. His chakra reserve - it's stated as a '3' in the databooks and therefore 'average'. Should consider than not all genetic traits are passed on. example: Tsunade, granddaughter of Hashirama, doesn't have Wood Release, nor any apparent affinity for Earth or Water.
3. Hair - it's a fair enough assumption, what with Kishi's tendency to make redheads Uzumaki related. examples: Karin, Kushina, Nagato. Consider they come from the same village, both are 'elite' shinobi etc it's not unfeasible that distinct hair colour/style is an indicator of bloodlines. Example: Naruto/Minato