If they wanted to know if you had dogs or babies and wanted to spy on you, they'd just transcribe the audio. People that have dogs or babies talk about them. Going to the effort to detect these and advertise it as a feature so you can secretly use it for marketing doesn't make a lot of sense.

At this point everyone knows you have a cat, dog or baby. Facebook, Instagram can scan your photos and see it. Same with Google via Photos' latest privacy changes. Google also knows if you ever get receipts emailed to you. Your credit card company and bank know, the CC company resells that data too. Shit, Keurig knows because their smart coffee maker scans the network and sees your baby monitor or smart pet food dispenser. All these companies are rediscovering and selling the same basic facts about you and your household.