If you are out with 2 small children, don''t both go in the water at the same time. And don''t get offshore and then have one of you searching in the sun for the body of someone who may have bitten by a shark. Be a responsible parent first. A bucket on a line works just as well for cooling you off, and if you really need that much cooling off, then think of the kids and how hot they are, so why should you be out there? (And I have been around kids circum with their parents.)
No matter how much you are scared of them, no matter how you want to blame "dive tours" for feeding them, remember - sharks will not jump into your boat to get you. They will eat what is convenient. I have had a 15 foot thresher circling a boat in the doldrums for 3 days. He lived, evidently, on leftovers we had to throw overboard, but we were not "feeding him", we just didn''t have the wind or fuel to move. He never made a move to jump on the boat. Don''t go for the evening swim together because it''s "romantic" and you will have no problem. I have known people who have sailed with their kids everywhere, the Atlantic, the Pacific, did a circum, etc., but never did I hear a worry from the parents about sharks eating them because they wanted to go for a swim.