Silicone does not contain latex. Silicone and latex are two distinct substances. Silicone is a synthetic compound that is similar to rubber and resistant to heat. Latex can be either natural or synthetic, but natural is more common. Silicone is a polymer whereas synthetic latex is made from a monomer.
A commercialized product to come from natural latex is rubber. There are over 12,000 plants that have rubber-producing latex. Natural latex is known to cause an allergic reaction in some people due to the antigenic proteins that are contained in latex. Silicone is known to be stronger and more resistant to puncture than latex in many uses. Swimmers often prefer silicone caps due to their durability, despite a higher cost than latex swimming caps.