my dad loves wii sports, he hasnt tried any other games yet, but thats because he wouldnt have time.
My mum loves WACHING us play wii sports (mainly tennis) and has tried once, but she faild terribly lol. however she said shell try n learn soon. but either of them are "gamers" lol.
I think your parents have a chance, dont forget they havnent actually seen how wii works, its completely different to what they think it is. no harm in tryin right?