Welcome to the Spotify Community and thanks for posting your question here.
We can confirm that, since your Spotify account is directly linked to Alexa through your Echo device, it won't be possible to play Spotify music via Alexa without the related Spotify account listening history and suggestions being affected.
You can find all the info regarding Spotify and Alexa in this support page article in case you felt like checking it out.
An effective way for the listening history and suggestions of your Spotify account to avoid being affected by your kids' streaming actions, would be for your kids to have their own Spotify account, either through Spotify Kids (if available in your country) or in compliance with our Terms and Conditions age requirements (which you'll find in the section 'Introduction').
Hope you'll find this helpful. Let us know if we can help with anything else!
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