Tigers have 38 chromosomes. Most species of cat have 36 or 38 chromosomes, with 36 being the usual number in Central and South American species and 38 being most common in Eurasian and African cats. Because tigers share a common chromosome number with other cats, they can interbreed with them.
Tigers are not likely to hybridize with other cats under natural conditions, even if their chromosome number makes producing offspring with other cat species relatively easy. Tigers are solitary and territorial animals and they are much larger than most other species of cat. Their range does not overlap with lions, which are similar in size but very dissimilar in habits. When tigers and lions are made to hybridize in captivity, they are able to produce fertile female offspring because both species have 38 chromosomes. The male hybrids are sterile due to Haldane's Rule, which states that the heterogametic offspring of a hybrid mating will be sterile. Heterogametic means that these creatures have two different sex chromosomes, X and Y. In cats, the heterogametic offspring are male.