So frustrated

We told my in laws today that we are having our third and they were like, 'Wow! When's the due date?' And then nothing- no 'how exciting!' Or 'congratulations!' Didn't mention the baby the rest of the day. They've always rolled their eyes at people who have more than two kids (the way THEY did it) or, God forbid, twins like my best friend. I'm the oldest of five so I get easily frustrated with people who act like more than two children is the end of the world. I was just hoping they'd grow up and actually be excited about our baby. But I guess three kids is just way too unconventional for them.