Sentence:  If we <WSD>presume</WSD> that human cloning may one day become a mundane, everyday reality, then maybe it's time to start thinking more positively about our soon-to-arrive genetically engineered pseudo-siblings. 
Meaning of the word marked with <WSD> tags:  To assume or suggest to be true (without proof); to take for granted, to suppose. (from 14th c.)