The most likely reason why the other neighbors in our solar system does not contain life, is probably because of the conditions of each planet. Very specific circumstances must be meet in order to achieve life, the form of life has to be able to mutate, adapt and change in response to its environment. The environment has to be right, can't be to hot, to cold, has to have water, some type of land and so forth. Another reason that life is not found on the other planet could be because a colliding object might not have contained the seeds for life at the time of impact.
The most probable reason Mercury does not contain life, is because the temperature varies to greatly. During the day on Mercury the temperature reaches 700 degrees Fahrenheit (370 C) and about 300 degrees below zero during the night. Mercury also has no atmosphere, the location being so close to the sun the atmosphere it would have had once, has been blown away into space. Mercury has no air, no water, no atmosphere, and nothing can grow on it because of the listed conditions. In short, Mercury is not very hospitable for life.
Venus, was once thought to be Earth's twin planet. Venus, a lush tropical planet hiding our distant cousins just waiting for us to visit them. That illusion turned out to be one of the greatest myths of all space exploration. Venus in fact is a large green house, with gases of carbon dioxide and deadly chemicals that would kill all life on earth if we were exposed to the same situation. Volcanoes spew molten lava, and hot gases continuously, the temperature of 900 degrees Fahrenheit creates a hellish nightmare of a planet. Hell is not the home that life would happily flourish.
Mars is the fourth planet from the sun, and thought to once contain life. Obviously today, life is not thriving, if it ever did exist. Water is said to be contained within the planet, so there is one element in which life could have once survived, but no oxygen. There is very little atmosphere, so a lot of radiation is received from the sun.
Jupiter is the first of the gaseous planet. A couple of obvious reasons for not containing life, are readily apparent. No oxygen, no water, to hot, and its all gas. Jupiter is about 90% hydrogen and 10% helium with traces of methane, water, and ammonia
Saturn has the same problems as Jupiter does. On Saturn, the strong winds that stir the atmosphere would certainly tear apart any living thing.
Uranus' atmosphere is about 83% hydrogen, 15% helium and 2% methane, not a very inhabitable area. Also life would not last the seasonal changes, winter would last for 42 years and the sun is not seen by that half of the planet during that time. When the spring equinox occurs, summer begins and would last for 42 years and the sun would be constant in the sky.
Neptune is considered it is seen that it is to cold, made mostly from methane gas, and has no land. Neptune has a thick atmosphere that contains winds that rip through the atmosphere at hundreds of miles per hour. Its like being in a very massive hurricane. Life would have no change to adapt and live.
Pluto on the other hand is more solid than any of its planetary neighbors, but at a distance of 5,913,520,000 km from the sun, Pluto is extremely cold and dead.