It may seem strange to some, but it's totally normal, to a limit. I started with my sisters and moms when I was thirteen and I know several of my friends were doing it with their female family members as well. The problem is, I didn't stop and it became a major fetish for me. I'm in my late forties now and still do it. My wife knows I sniff hers, but has no idea just how far beyond that I have ventured. I have sniffed her mothers, all of her sisters, my ADULT nieces (I'm not a monster), nephews wives, aunts, daughter in laws, neighbors wives and daughters, you get the picture.
I'm not always the first to volunteer to care for pets or house sit simply because I'm a nice guy. I am not posting this to brag, in fact, it's quite embarrassing. Consider it a public service announcement to all you ladies on the forum. Just be careful where you leave your worn panties, workout shorts, swim bottoms, tights etc. If it carries your feminine scent, a good sniffer will will hunt them down. We have a hot tub and I have sniffed so many panties after women have changed into their swimwear and left them laying with their clothes I've lost count. My wife has never figured out why I'm always the last in the tub.
If you have a house sitter when you go on vacation don't leave any worn panties in hampers. Don't leave them in hampers of restrooms that guests are going to use. Don't leave them lay in plain site in laundry rooms or even bedrooms for that matter. Keep them in hampers hidden in closets, etc. If you change into swimwear at someones house slip them into your purse or a beach bag that you take with you. Sniffers look for quick opportunities and 99% of the time are not going to dig around at the risk of getting caught. Nothing is more embarrassing than getting caught with a pair of panties pressed against your face while you are masturbating!