To gauge the persona of your competition's customers the best things to do would be:

1) Go to your competitors' websites, and look at how they are presenting themselves. For instance, look at:
A) The images they use: Age and other aspects of the people in their images. Are they targeting families, or certain family members, etc.
B) The words they use: The specific problem they're pitching a solution for. For instance, maybe they say, "for busy people that don't have time for xyz"
C) The format of their product: For instance, do they have an app for a younger crowd, or is it formatted for an older crows?
D) The price of their product(s)

2) Do a google search for your competition's name and see who talks about it and how. For instance, if they have an app, read the app reviews and look at the type of person that's leaving them, and the type of review they give. Go to online forums and see who's discussing it / recommending it and how they describe it. If you can't find any existing forum discussions of your competition, go to popular forums and post your own comment/question about your competition and see if anyone responds (i.e. see how many people who read that particular forum also use your competition). You could even post questionnaires on those forums targeted at your competition's customers. In the questionnaire you could explicitly ask how they found out about the product.

If you'd like more detailed advice related to your specific product, or have any other questions, let me know,

best,

Lee