a therapist would not be trying to convince anyone that social phobia is biological, they would want you to believe it is learned behavior that can be un-learned..i know this, ive had social phobia issues since the first day i entered kindergarten, age 5..whether i learned it somewhere i dont know but i doubt it..i think it is biological with me..its not just a 'low confidence' thing..if it was, you are saying i was suffering from low confidence at age 5?that doesnt add up to me..many researchers will definitely report that a genetic link is responsible in many cases of social phobia, it is somehow hard-wired into many of us..
There is always gonna be a genetic link since its very common for it to pass generation upon generation, but it passes from father to son to son to son by behaviours learnt from fathers .
As the saying goes like father like son ,but to say that a behaviour can be genetic is completely ludicrous .The reason it helps people sell programs and stuff is because those who suffer from it love to believe its not their own fault and theirs nothing they can do hence genetic.
"We can help you with your genetic ailment" it makes you more inclined to pay a doctor and accept you have an issue if your told its genetic.
I can not say what all is your particular issues or how you have it as there is millions of reasons why a person has it ,but i think low confidence at 5 i would say is not only possible but very common.
Whatever you reasons for it i think its a cop out to say its genetic, and i don't like to criticize as i know how bad thing can affect your life.
If you think its genetic then either of your parents had it? they passed it on to because you copied them possibly ,not because it's genetics.