Space clouds and you!

Space isn't entirely empty, there are a lot of loose particles, gas, and plasma spread through it. Interstellar clouds are areas of greater concentrations of that material. There are a number of interstellar clouds in our vicinity of the galaxy. In fact, we are currently moving through the Local Cloud and headed towards the denser G-Cloud which Alpha Centauri is located. Of course, all of this takes millions of years.

Could the passage through interstellar clouds influence the Earth and Solar System?

Also within our vicinity is a ribbon of clumps of denser interstellar medium known as Local Ribbon of Cold Clouds. It is theorized that 3 to 4 million years ago we passed through one of these dense areas. 

The Solar System is protected by the heliosphere. The heliosphere is a bubble of charged particles the Sun emits that buffers the Solar System from interstellar radiation and materials. However, it is believed that the encounter with one of the dense Cold Clouds could collapse the heliosphere significantly and expose the planets, including Earth, to the interstellar medium. There is some geological evidence that this did happen at the time we may have passed through one of the Cold Clouds.

There is then the question as to what, if any, effect this may have had on the Earth? There is a rough correlation between the time of passing through the Cold Cloud and the start of the Ice Ages. Correlation is not causation, but the timing is interesting. If nothing else, the rain of interstellar particles and radiation causing noticeable climate fluctuations seems to be both possible and plausible.