Terrified of walking the same path again

I have been very relaxed about B.
He is my second child. 
He was not born prematurely.
I am more confident and have had no concerns about him at all.
But today something knocked me sideways.
A friend with a baby of the same age is saying Mama, and has apparently been saying Dada for a while.
Another friend with a baby of the same age has been saying Dada for a couple of months too.
As with C at this age, I am yet to hear a consonant from B, yet alone a recognisable word in context.
Like C, there is no babble, no chatter in his cot in the mornings.
No ba ba ba, ya ya ya.
I hadn't really thought about it until today.
He is 10 months old next week.

 C and B at approx. 10 months old                                          

C suffers from severe speech delay.
It is not unheard of for this to be hereditary.
It is therefore not impossible that B could suffer too.
I felt sure he would be fine though.
That being the second child in a busy household with lots of chatter he would pick up words more easily.
I had convinced myself it was another unfortunate repercussion of C's prematurity.
However now I am scared.

Having a child with speech delay is difficult.
I don't want another one of my children to have to suffer with the frustration of not being able to express themselves.
I don't want to go through it again.
People already judge that C's problems are due to failures on my part.
Not reading enough, not talking to her enough.
This will only increase if I have 2 children with problems.

Yes it is still early days.
He still has plenty of time.
There is no rush.

But after today I cannot help but worry for him.
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