I love his sister. She's just an interesting character. She is extremely successful and is the antithesis of MC's worldview and so puts him into an awkward predicament.
@Tamerlane agreed, I wonder how much of this is him being an unreliable narrator? He described his family as impulsive screw ups, and the description of his father and brother superficially fit that this chapter, though it was a very shallow explanation. His sister doesn't fit it at all, but I can kind of see how from his POV he might feel that way from the little he sees of what she actually does & how he only sees her at home off the clock when she's more trying to relax.
What if we find out later his father is a real archaeologist & his brother is either a heart surgeon or cardiologist and the learning about women's hearts thing was literal, and his whole problem is he only sees them all when they're trying to de-stress from their jobs?
Associate professor of astronomy sounds pretty respectable to me. And we know the best researchers/professors are the ones who don't give a damn about their personal lives.