Mean sister-in-laws

Colleen
So today was out 20 weeks scan and everything went really well. My husband and I were super excited so we texted all his family the good news. No body responded but his mom. His sister and sister in law are both pregnant right now (37 wks and 29 wks). We were so happy for them when they would txt their baby information and even went to their gender reveal parties but now they don't even have the decency to say "congrats" or "so happy for u". Why are ppl so mean?