Obviously it's a concern - but there again I should jolly well hope you - or I, etc - would spot the symptoms somewhat quicker than your average Joe. However I really don't think it's worth losing sleep over - parents already have enough things to worry about for their kids!
There's no diabetes in my family up to my generation that we know about. However one grandma died in approx. 1927 of 'heart failure' when her son, my dad, was 12 - so neither he nor his big sister (14-ish) had a clue what might have/could have caused the heart failure. Stuff like that was certainly not discussed in front of kids in those days. I never knew a single person from her side of dad's family. My maternal grandma was one of about 12, mom knew 2 cousins, only one of which we met. Nobody from her dad's family either.
Very close families both of them. Oooer, I think the word is 'closed' LOL
Contrast this with the photo my husband has, with 5 generations on it! However - ALL his mom's side - nobody from his dad's - even though he was on of about a dozen! So if either of Pete's kids, their kids, their grandkids comes down with whatever and anyone asks 'Does Beri Beri run in the family?' - nobody will have a clue.
What difference does it make anyway is what I'm getting at - knowing it runs in the family doesn't mean you can do anything to PREVENT them getting an 'inherited' condition - so worry about where to go on holiday, instead !