Grandparents, Aunts and Uncles, and close friends will largely treat your children the way you do. If you speak softly and ask them nicely to stop doing something you feel is not appropriate, they usually will too. On the other hand, if you punish them, treat them as incompetent, and speak to them harshly, then those around you will assume that they should too - because that is how you want things done.
I used to think that some family members were "walking on eggshells" around us - and that may be partly true - but then I realized that this is a much more positive way to look at their behavior. Yes, it may make others uncomfortable because they are not used to it. Yes, they may not know what to do or say sometimes because they've never seen or experienced gentle parenting in action (and hence the uncertainty and "eggshells".) But over time they will start to see what works and what doesn't and they will begin to mirror your behavior.
I've seen this in my own parents. I specifically remember a year ago when Gerry was crying because he didn't want me to go on a swim with my dad in a lake. I was feeling exasperated because it wasn't like I was going to the moon - and also I'm with my kids pretty much ALL. THE. TIME. But you know what? My 4 year old boy still liked to keep me close. Anyway - my dad said something to me that made me feel so good. Basically he said, "He'll grow out of this - look at Marisol and how independent she's gotten!" It was such a boost for me to hear those words coming from my father. My dad loves me very much - this I never doubt. But he also thinks I am a total hippy and I know sometimes my ideas seem just a little bit out there to him - so to hear my own philosophy coming back at me in a positive way, in a moment when I really needed it - well, that was amazing! (And you know what? At 5, Gerry still likes to have me close a lot - but he's also loosening up and his comfort level for space and time from me is increasing! Imagine that, he's growing up!)
This is another huge benefit of choosing to parent this way - it's really isn't about just you and your kids. It's about everyone you come in contact with. People can't help but learn from the examples you live out every day.