How to switch off thumbsdown emoijis in Facetime?

How do I stop thumbsdown emojis randomly appearing whilst talking on Facetime? My father called me to tell me that a family member is seriously ill and in hospital, and during the entire conversation, at the most inappropriate times, thumbsdown emojis kept on randomly appearing. How do I stop this? I have looked through the menus and can't see where to switch off this feature - it is not something that I've ever turned on. I really don't want it to happen again.