I would tend to agree with Aquafeline that it's the disposition rather than the age. I would say though, that the statistics from Venrays auto statistic generator would probably show that older people are more likely to be more open and adventurous, but people mature sexually at different ages so it's very individual specific.
I used to negotiate tickling into my relationships, even back when I was 18. I wasn't very shy about going for it though. If you are passionate enough about your request, and your lady really loves you, chances are she'll play with you. I never had a single one ever say "no". The key there though, is to be honest without being *needy*. I've attached a message at the end of this post that I sent to a friend in the newsgroups a couple of years ago. It's primarily about a foot/tickling fetish, but the idea remains the same regardless.
There are ways to introduce it without ever admitting you actually have a fetish too. One trick I used was to leave a copy of Variations lying around (when I was young, that was about the only magazine with tickling stories), let her read some of it together with me, and let a discussion spawn from different stories there including the tickling stories.
Today a good way to accomplish this would be to print out several good sexy stories from the net, and let one of them be a favorite tickling story. You can approach it with the idea of "Hey, we have a great sex life, the sky is the limit, let's play! Here are some cool stories I found." The conversation can grow from there.
Okay, here's the post that can give you an idea of *how* to approach it if you do decide to go for it openly. This method never failed for me, but take it for what it's worth to you...
"Use that gentlemanly charm and *seduce* her to your way of thinking. If she is willing to compromise and let you try things with her, even if she says "I prefer you didn't", or "I don't want that", it gives you the perfect opportunity for seduction. In my experience, though I'm far from being an expert on women, there has been nothing a woman wouldn't do for me or let me do to her under the influence of passionate seduction. The key would be to be honest and extremely passionate. Don't do anything robotically.. that may sound stupid, but the tendency is to try to detach yourself from your passions to avoid being hurt by rejection. This would run along the lines of telling yourself "if I don't let myself get excited about it, I won't be disappointed".. well, that's failure waiting to happen. You have to get excited, get pumped, work yourself into a passionate frenzy.. and then let that passion come out naturally in your voice, in your touch, in your eye contact.. passion *is* seduction.
And whatever you do, don't try to play on her sympathies. If you talk about your fetish saying things like "no one understands me", you move away from seduction and at best will probably trigger her "maternal" instinct, or at worst, she'll think you are whining. You cannot seduce a woman in maternal mode because she'll view you as someone to coddle rather than someone by whom she wants to be ravished (and your goal is to put her in a state of "take me now you man of my dreams"). The seductive way to engage the conversation would be to look directly into her eyes and very softly but passionately say "god I love the idea of driving you completely mad with arousal simply by touching your feet. I love the thought of seeing your eyes glaze over as your passion builds with each touch. I love the combination of feeling the softness of your skin while listening to you moan softly as each stroke of my tongue takes you to a higher level of intensity. I love the shape of your feet, I love how they wrinkle as I touch them, I love how you giggle so innocently.. god, you have such a seductive laugh when I lightly tickle.. it's different from your normal laugh.. you have a sexy laugh to begin with, but when I tickle your foot, your laughter sounds so passionate, so completely erotic....god you turn me on that way. I get going just thinking about you that way" Never break your eye contact.. stare into her eyes so that your entire world reduces itself to that moment. You are changing the focus from "your fetish" to "her sexuality". You are making her see how your fetish and her sexuality go hand in hand and will make you both explode with insane arousal, etc...
See, you don't want her to think it is the fetish that turns you on, but rather it is HER in every way.. that the fetish would be nothing without her.. that she is that alpha and omega of your foot touching world...you love the way *she* laughs and reacts, you love how *her* skin feels, ... don't just describe how you love to touch feet, or just love to tickle because that detaches the fetish from her sexuality. You want her to understand completely that you love to touch *her* feet, and love to tickle *her*, and that taking *her* that way drives you absolutely wild with desire because she is such an incredible woman.
And lastly here, when she does let you do it under the "compromise" label, be sure you let her see how it affects you, be honest with your arousal.. let her hear your deep moans, let her see it in your eyes.. make lots and LOTS of eye contact so that she can see how "her sexuality" drives you mad.... work mostly on her heels and toes because she is completely open to that, and ease her into the soles, but with each touch on her sole, let her see or hear how it drives you crazy ... you want her to begin to think about it as a *sexual power she possesses* as opposed to a fetish you have or something she doesn't care for.
What I've said may sound corny but I do know that honest passion is amazingly powerful. But, you have to remember, it's not a game or a come on line.. you are manipulating her, yes.. but you are doing it honestly, the way nature intended."
Well, that's it. That's my secret for seducing an amazing number of women who didn't share the fetish into *wanting* to try tickling.
Good luck!
David