Adenoids are a mass of lymphoid tissue that sit behind the nose. If they are enlarged, they may block the ability of the eustachian tube, which extends from the middle ear to the adenoid region, to allow fluid drainage from the middle ear. Bacteria may also remain in the adenoid region, and may further lead to risk of recurrent ear infections. There are certain 'risk factors' which have been shown to put a child at increased likelihood of having recurrent ear infections. For infants, taking the bottle to bed at night may result in bottle feeding 'refluxing' into the back of the nose, and even eustachian tubes.
Breast feeding is associated with a lower incidence of recurrent ear infections in infants.
The combination of feeding in an upright position and exposure to protective maternal antibodies contribute to this. Tobacco exposure is known to increase the incidence of otitis media in infants and young children. You should not smoke. It is bad for you and for those around you. That goes without saying, but still needs to be said.