I know you've already said you wouldn't get a dog from as pet store so this is more of a general statement; pet stores will also lie about where their dogs come from. I've read about this happening many times here on YT. They will say they bred the dogs or their mother or best friend or whatever even though they are getting them from mills or brokers who got them from mills. There is one near me who will swear up and down that they work closely with a few friends who breed a few dogs.
From the number and constantly changing variety of breeds there is no way but regardless, that isn't how a good breeder sells their puppies.
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"If you have men who will exclude any of God’s creatures from the shelter of compassion and pity, you will have men who will deal likewise with their fellow men." — St. Francis of Assisi, 1181-1226