What determines taste in literature?
I suppose out there are texts written by learned folk, backed up by research on this subject. Without easy access to such sources, I can only offer suggestions.
My gut feeling is that taste: in literature or in many other things: is determined by the personality of the individual. Sure, there may be other influences such as peers , teaching, or the media, but a strong person who is true to their own beliefs is likely to shun these factors, at least to some degree, and like what they like because it appeals to them, and not because their liking seems to help them fit in with the crowd.
Good taste in literature is fostered by wide exposure to many styles of writing. Even small doses can be enough to sway a person one way or another. Isn’t the appreciation of what is perceived as ‘good’ heightened by exposure to what is perceived as ‘bad’?
Parents have a huge role in steering kids into a love and appreciation of reading. Choose well and wisely, and hopefully your offspring will carry a love of reading with them throughout their lives.