Janie, your observations fit with the study I wrote about, which suggests that lefties have not inherited a preference for either side but have ended up with left. You might find that righthanded relations are similarly ambidextrous, though haven't bothered to develop the left hand ability as much as a lefty has to develop right hand skills.
My Dad was a lefty, though switched for writing, and used his skills to teach knots in the Engineers as he could demonstrate facing the troops, who did not need to switch round what they saw. I have been able to learn some things lefthanded.
I learned to play bar billiards left handed, because the person who taught me was a lefty and didn't bother to tell me. I only realised I was playing lefthanded when the same person exclaimed that he hadn't known I was a lefty. I wasn't able to switch back, which of course means I'm not lining up with my dominant eye so well.
I did try to explain about the scissors. The link I gave has a page explaining the difference with piccies, which might be easier to understand. The shop also sells lefthanded secateurs, which would have the same problem for a lefthander using them as scissors, though probably not as pronounced.
Something that often puzzles me is the sort of saucepan with a small lip. when designed for righthanders, this lip is on the left of the handle, so you can hold the pan in the right hand and our out towards the left. But this is not very helpful if making something that needs stirring while pouring, like custard, since you need to hold the pan with the left hand and stir with the right. I hadn't noticed this was a righthanded pan, until I saw a lefthanded version advertised. What was in their minds? (Ihave pans with a curved rim all round.)

Penny

Penny