When I was growing up, we only had a bath twice a week, and because the immersion heater had no thermostat and was slow and expensive to run, my sister and I shared bath water, and so did mum and dad.
Dsis was younger than me, so she went first, and got the bath water whilst it was hot and clean. I had cooler, grubby water, and I had to tidy up the bathroom, hang up the towels and rinse the bath out.
When we were small, I had a later bedtime, so I felt it balanced out - she came out ahead on the bath thing, but I got to stay up later - but when we were teenagers, we had the same bedtime, and I felt it was unfair that I never got the clean bath water, and dsis never had to do the tidying up, so I asked mum if dsis and I could take turns going first - it seemed fairer to me, and I couldn’t see any reason why mum would refuse - but she did.
Looking back, I am sure she preferred dsis to me (this isn’t the only clear example of favouritism), plus she always went first out of her and dad, and maybe she bought that, if she accepted it wasn’t fair for dsis to go first all the time, she might have to let dad go first sometimes too.
One Christmas, she put knitting needles and yarn in my stocking - I enjoyed knitting - but it was for me to knit a scarf for dad. To me, it felt like it wasn’t really a present for me, and for once, I had the courage to say something - only for mum to guilt trip me into backing down.