Why brands have variants

Haven't we heard this before: Why are there so many variants in a brand family? Is it logical? One way of understanding this is by likening brands to personalities.
Personalities can be versatile, but there are limits to how versatile they will be considered...

Just like in school we might have had one classmate who was very good in maths and in chess. And then there was this other classmate who was good in football and in running.
It's funny but true that even if the first classmate who was good in chess and maths ran well one day, it would soon be forgotten and in fact not even noticed. That is because images once formed, don't change very easily.
Now look at another example.
Mercedes makes great cars. So their logic for making the small car is - if we can make a large car so well, then surely we can make a small car too! But as you know, the customer doesn't really associate them with the small car and so they find it difficult to sell. It's also got to do with the DNA of the company. But on that, a little later...
Let's look at another example. When Cadbury launched the Dollops ice cream parlour, guess which flavour they sold the most. Yes, chocolate! And when they launched biscuits? Again, chocolate!
A funny one - would you buy potato chips from Intel??
Okay, now back to the point. When we say ICICIdirect.com, the world thinks of us as online - a format which is for self directed share trading. And online is the opposite of offline! Because online seekers are culturally middlemen averse. While offline seekers thrive on intermediaries, when we say "Securities", we accurately point to this category and at the same time, we do not carry the online image hangover.
There are some people who are suspicious of any intermediary - they think their driver steals petrol (no one has ever seen one do that though! I wonder where he sells it!); of dealers, and of brokers. They think middlemen stand in the way of direct and transparent access. They think middlemen distort the truth for personal gain. This is a typical salaried class mind at work. Such people love the online world.
And then there are people who are exactly the opposite. They infact thrive on other people for 'getting their work done. If something has to be done, they find someone to do it for them, for a fee.
The former seek self help formats and even trade online while the latter seek middlemen who will their respective needs uniquely.
Now what was that about the DNA?
Well there used to be a little gospel which went like this - twenty minutes into a board meeting in ITC on the subject of diversification, someone would puff at his cigarette and say "But you know in tobacco....."!