This is probably on my parent's end, but I figured it can't hurt to check here...:- )

Recently, when I text my parents, who both have iPhone 4's w/ a shared AT&T plan, from my personal phone, a Droid Pro with Verizon, my texts to them end up in one text message window, while their replies end up in a seperate text message window. That is how it appears on my phone.

Doesn't happen with any other person I text, including my work phone, which is also an iPhone 4 w/ AT&T.

Is this possibly something I accidentaly did on my phone that just affects them, or is it just something on their end (which they would never figure out...:-) ).

Thank you.