Years ago, I felt the same way about convincing family members to play chess. Feeling like you are begging them isn't the way to do it. The reality is that you can't force them to play and enjoy it. It's like the saying, "you can lead a horse to water, but you can't make them drink."
The best you can do is let your sister see how fun chess can be for you and create the environment for them to try if interested, but there's a good chance they'll never be interested and that's their choice to make.
The same is true for chess-loving parents wanting to get their children into chess. You have to have them around the chess environment. Maybe play with the chess pieces, or see you playing chess; let them get interested naturally and create a fun learning environment for them if they do show interest, but some will never show interest and that's their decision for themselves.
any ideas?