I have DSCs who are now adults, early to mid twenties. I lived with them as a SM for their teenage lives, although now they live on their own or at their mums. It started off OK but creeping resentment came from the older ones, and now none of them engage with me on any level.
I've been given advice, here and from others to 'let them go' their own way, and that when adults they will start to acknowledge me more, as they mature. But it hasn't happened.
For example, they all came around the house last weekend, but as usual, just sat there and I had to be the one to ask, to enquire, to smile, to discuss their lives. I never, ever, get asked about mine, they never play with their little brother, they just sit there looking bored until their Dad bounds in and makes a huge fuss of them.
I have to say that they are like this with their grandmother too, but she just accepts it. And the last time DP asked them to play with their little brother it ended up in a huge argument between them... 
I keep up being distant but supportive and kind, send messages of congratulations, remember all birthdays, support any of their efforts. But I have to say I'm a little sick of it! I'm not sure I am interested anymore as it is so one sided.
Does it get better? Should I jokingly suggest they talk about me one time?! I could just sit in awkward silence whistling a tune?