The disagreement was about washing towels together with everyday clothing. I always mixed them in one load, while my sister insisted they should be separated. Her warning was not completely unreasonable.
Towels are thicker, heavier, and much more absorbent than shirts, underwear, or trousers. Once soaked, they hold extra water and detergent, changing how the entire load moves and rinses.
Lighter clothes may rub against rough towel fibers for longer than normal. Over time, that friction can wear delicate fabrics, stretch softer items, and leave lint or small pills on dark clothing.
There is also a hygiene issue. Used towels stay damp and collect skin cells, oils, makeup, and microbes. They often need a warmer, longer wash than many clothes can safely tolerate.
If everything is washed on a cool, gentle cycle, towels may not be cleaned thoroughly. But a hotter, stronger cycle can fade, shrink, or damage delicate clothing.
Drying brings another problem. Towels need more time, while thin clothes may already be dry. Keeping them together can overdry lighter fabrics, increasing static, wrinkles, and wear.
Mixing them once will not destroy a wardrobe or automatically make anyone sick. Sturdy cotton clothes can sometimes share a load with towels if colors match and the drum is not packed.
Still, separating them is usually the better habit. Towels rinse and dry more effectively, while clothing keeps its shape and texture longer. The extra cycle is inconvenient, but it avoids several hidden problems.