What I like about this is that you have to use parish records too. You can find children and their parents but usually you can't find grandparents. Don't forget about the grandparents - they could still be alive.
I'd also like to say, take note of how the people in the family are arranged and be open minded. I had one family where the ages were (they thankfully forgot to round them) 41 John, 48 Sarah, 18 Joseph, 21 Martha, 16 William, 12 Elizabeth, 13 John, 6 Sarah, 3 Emma, 8 months Jane. The ages looked fine so I assumed they were all children. I wanted to know the mother's maiden name as the marriage wasn't on the IGI. I ordered the birth cerificate and I got it. It said the parents were Joseph and Martha. Once I saw that, I realised why they had not been put in order of their age. As they don't show the relation to the head of the household in the 1841, you need to take much more notice of how the family is laid out on the image.
Andrew