Yes, there is such thing as human nature. Humans aren't above the rest of the natural world, above the instincts that all animals are born with. Last I checked, we're still still living beings. Our higher cognitive abilities don't make us un-natural. When we talk about human nature and science-worshipers scoff and mock us, they're only in denial as to what humans are. We're not artificial lifeforms, as much as they'd like that to be true. We're part of nature, and nature is part of us.