I have a 7 month old St Bernard who jumps & runs at my wife and kids when in the garden. He becomes uncontrollable. Is this the 'Alpha Male' scenario where he is trying to become boss. HE wont act that way with me but it is becoming a worry

Hi,
He's becoming a teenager! And we know how they behave (dogs and humans)! If they think they can get away with something, they'll try it. Very few dogs actually want to be the boss, but they will take that place if it is left available - any leadership is better than none. When he starts being a git either put him indoors, or do some simple training with him. That way you can praise him for good behaviour and he'll become less excited.

Sometimes people mistake good old "playing" as being dominance too .
Different breeds have different characteristics that sometimes worry people too . For example Staffys like to growl when you play with them and their toys but it isnt being agressive - its the way they are .