We may not believe it, due to our materialistic bent, but blessings and curses are real and powerful in the 21st century.
Blessings and curses were very personal acts. Hebrew words translated as bless occur 131 times in 121 verses in the NASB translation of the Old Testament. Hebrew words translated as curse occur 105 times in 94 verses in the NASB translation of the Old Testament.
Blessings and curses were considered to release a very real power which could determine the character and destiny of the recipient (Genesis 27:12). A blessing was considered to be a visitation of the grace of a god and a curse was considered to be the visitation of the judgment of a god. Polytheists such as the Babylonians and Egyptians believed that pronouncing a blessing or curse could force the deity to do the will of the one who was performing the act. Monotheists such as the Jews (in their better days) believed that a blessing or curse simply reflected the future that the sovereign God had ordained.