Absolutely. Personally I haven't made much use of NoSQL, I'm sure there are plenty of use cases, but for ancestry I would still use a relational db.
I do see how nested objects might look like a perfect fit for this, since families are literally "nested objects". Perhaps there are plenty of advantages to using NoSQL and shaping the data this way... but the thought of creating an API With that structure is terrifying to me, haha.
Question to OP: are you using this structure for a live api/website I can take a look at? Does each node have an absolute ID? Do you normalize your data? Maybe I'm thinking too much in relational terms here? I'm genuinely curious about this.
Your mother field should resolve to a Person type, with a mother and/or ancestors field, which would be a graphql list type of the Person type.
Something like this: