Hey, You should never feel ashamed to tell your parents that you want to play baseball. Always remember that your parents were teens themselves and have had to make their mind up about situations 2 and
3 times over; just like you.
They will accept that you may not have liked baseball but tastes change and they will understand this. Girls play baseball too and this would never be an issue for many, in fact they may even like to watch a game with you.
Perhaps talking and hanging out with friends who already play and enjoy the sport might help your parents see that you are taking more of an interest in the game?
There really isn’t anything that you should be embarrassed about.