I agree with djole on that statement. When I was 6, I was forced to learn the piano and resented every moment of it. It was only 11 years later now that I took up the electric bass with Interest which adds to the desire to learn more. Just my 2 cents.
I was 8 or 9 when my parents put me and my older sister in piano lessons. The trip to the music store was an adventure and went something like this:
Parents: We're going down to the local mom and pop and you can pick out an instrument!
Me: Woohoo! Guitarsville!
<drive to music store>
Parents: OK, you two, take a look around and see what you'd like to play.
Me: <pointing> That black Gibson Les Paul Custom right there, that's what I want! How cool?!
Parents: Uh, are you sure? I mean, it's neat and all, but isn't there something else you'd rather play?
<meanwhile, sister has disappeared to another part of the store>
Me: Well, here's one that says Fender, like on a car, that's funny. How about this one?!
Parents: Uh, hrmm, you don't really want to play guitar, though. All those strings and then you have to have an amplifier and who would teach you?
Salesman: We offer lessons...
Parents: <cooly> Let's go find your sister.
<find sister in piano section>
Parents: Ah, yes, this is more like it. How about something like this, Dick Seacup?
Me: You said we could pick what we wanted to play, I don't want to play piano, I want to play guitar.
Parents: Well, see, we can only buy one instrument and your sister wants a piano so...
<piano purchased>
Six or seven years of non-stop fighting about piano ensued. They finally had enough when I was 15 or so and let me quit. I did learn how to sight read, though, and still can (although not as well as I could). I didn't touch a keyboard after that until I was 23 or 24, when I bought a Juno 2. I did start playing piano again in my 30s, wondering how I could have forgotten so much technique. I still play from time to time and actually enjoy it now, but maybe that's because it's on my terms. I find reading music for guitar to be impossible, though.
Anyway, to the question at hand. My younger two sons were both given the opportunity to pick an instrument. The older of the two picked guitar, the younger picked drums. We bought them decent instruments and set them up with lessons with the best teachers we could find locally. They stuck with it for three years and then lost interest, as sports were more exciting. Which is fine, but at least they had the exposure*. A couple days ago, the older one--now 12--told me he wanted to start taking guitar lessons again. We'll see, maybe after the first of the year.
My recommendation would be not to lean on your son to play bass just because you play bass. I don't think that would work out any better than those former high school football jocks who push their kids in to sports because that's what dad did. Too much risk of resentment. I'm one of those people that believe musical exposure is important but you need to let the little sprog figure out which instrument holds the most appeal for them.
* And I wound up with this quirky junior drum set that I can bang out a solid four on the floor on.