He's just not that into it

I just find it so amazing how different two kids can be when they're from the same family - I just don't get it.  Olivia took right to her first food of rice cereal and loved every bite of it.  In fact she continued to eat the baby cereal way into her first year!  She has texture issues and the smooth texture of the baby cereal was perfect for her.  We added several things to it as she got older and sometime after she turned one we started adding regular oatmeal to it little by little.  But she loved the stuff and wanted it every morning for breakfast - I thought I would be feeding her oatmeal for the rest of her life until she finally discovered bagels and cream cheese and now she eat a much greater variety.  Jack on the other hand is completely different!  He will be 6 months on Monday and he still isn't eating cereal.  I've tried atleast 15 different times.  I've made it thin and thick and everything in between.  I've made it with water, formula and breast milk.  I've tried it in the morning, afternoon and evening and I recently mixed it with bananas and he still hates it.  

He has his 6 month wellness visit a week from today and I'm just wondering what the doctor will say.  He's also not gaining much weight - Olivia wasn't a big baby either, but I don't think that Jack is even as big as she was at this age (I'll have to check the baby book) and he had a 1/2 pound head start on her.  He seems perfectly content with breastfeeding - I try to offer additional feedings and try to keep him eating for longer periods of time, but when he's done, he's done!

So, any suggestions?  What were your kid's first foods?  Did you always start with cereal?  I gave him a few bites of banana the other day and he seemed to like it better so I'm thinking of skipping the cereal all together.

I also know there are developmental signs that a baby is ready for solids and Jack is getting there - he is getting better at sitting, but still needs support, the tongue-thrust reflex isn't as strong - he will not immediately push the food from his mouth, but it eventually comes out, he's VERY interested in the family at mealtime - he watches our every move as we eat and drink.  So am I just being overly eager to start something he's just not ready for or do I need to encourage it a bit more?  Should I stop nursing him before offering solids?  Should I just chill and not worry about it all?  or D - all of the above.

You would think that once you've been a mother of a baby that you've learned all you need to learn, but I'm slowly finding out that one size does not fit all when it comes to children.  So what I did for Olivia isn't working for Jack - what worked for your kids?