Curses are real and they're very serious and powerful because they summon demons. The spoken word is very powerful! For instance, when a mother tells her children they are ugly and will never amount to anything, she has cursed them and, chances are, they won't amount to anything!
Curses don't even have to be made out loud; we can curse ourselves and others by our deeds and actions, and those curses won't be broken until someone along the line repents and turns from the generational sin.
Example: One of the eight men my mother married was a raving pedophile who sexually me for years when I was little. Well, when his aged father came to live with us for awhile, he too, tried to have sex with me. That's when I realized at the tender age of 12 (without even knowing God at the time) that this thing must have been "generational" or "passed down" somehow, for who knows how many generations. Turns out, my half brother (the pedophile's son) also turned out to be a pedophile. In his case, he is a bi-sexual pedophile! I shudder to think that he may have passed this curse on to his own children....
Somehow, each father through the years was subliminally or overtly passing this sick desire down to his kids (whether male or female). This type of stuff will remain a "curse" until at some point somebody recognizes that having sex with little kids isn't a normal thing to do for many reasons (including that it ruins everyone's life along the way), and they stop AND repent for themselves and all of their ancestors and give themselves totally over to YHWH from that point on.
Most people don't recognize generational curses (habits, quirks, carnality, things that are ungodly) and so they keep on doing what their carnal natures tell them to (drugs, alcohol, sexual things, gambling, being abusive, etc), and in the process they destroy their own lives, and the lives of their immediate relatives or others. Children learn behaviors from their parents/guardians and pass those behaviors on to THEIR children! A curse like that can only be broken when a person recognizes he/she has problems and BREAKS those habits by giving him/herself to God and repents and then refrains from ever doing those things again.
The Bible tells us: "Like a fluttering sparrow or a darting swallow, an undeserved curse will come home to roost" (Proverbs 26:2). In other words, those who attempt to put a curse on one of YHWH's people, may end up having cursed themselves, instead. For instance, every male in my adoptive father's lineage was cursed by their mere actions as indicated by the fact that they passed on their cursed behaviors....
"Spells" in the Bible are always described negatively and are considered "detestable" to YHWH (see Deuteronomy 18:10-11); i.e., child sacrifice, witchcraft, sorcery, divination, or necromancy (consulting with the dead. Micah 5:12 says that God will destroy witchcraft and those who cast spells and Revelation 18 describes spells as part of the deception that will be used by the antichrist and his "great city of Babylon" (v. 21-24).
Believers do not need to worry about anyone casting any sort of pagan spell on them ((Romans 8:11). Voodoo, witchcraft, hexes, and curses have no power over us because they come from Satan, and we know that "the one who is in you [Messiah] is greater than the one [Satan] who is in the world" (1 John 4:4).
The thing is, we can overcome ANY spell or curse with prayer - Halleluyah! Whenever something is "not right" in your life (no matter whether it's a general curse or from some outside source), simply pray for YHWH to take it away and totally give your life to Him. Satan has no power over those who belong to YHWH!