That has some super creepy implications--imagine the father of a teenage girl wondering why he's suddenly seeing so many internet ads for maternity products, for instance.
Can't find it atm but there was at least one story of someone being outed as gay due to ad targeting. For things like that, if you can think of it it probably already has happened, and if it hasn't, it will in the next 10 years.
https://www.forbes.com/sites/kashmirhill/2012/02/16/how-targ...