This is the history (ESV: These are the generations) is the translation of the Hebrew word “toledoth.” Toledoth derives from a Hebrew verbal root which means to beget (a man as subject), to bear (children), to bring forth (a woman as subject). So, the meaning of toledoth became descendants, offspring. But it can also mean genealogical tree. As part of the toledoth expression ("This is the history of x") it has a metaphorical meaning. It then introduces the history of the offspring of the person named in the expression (e.g., Genesis 5:1 – 6:8).