diff --git a/build/neuralnetwork/core/Genome.php b/build/neuralnetwork/core/Genome.php
index 1acf4ea..d85cb27 100644
--- a/build/neuralnetwork/core/Genome.php
+++ b/build/neuralnetwork/core/Genome.php
@@ -145,6 +145,47 @@
 			return true;
 		}
 
+
+		/* APPLIES A MUTATION ON THE Genome WITH A SPECIFIC @threshold
+		*
+		* @threshold<double> 									Mutation threshold
+		*
+		*/
+		public function mutation($threshold=0.5){
+			/* (1) Checks @threshold argument */
+			if( floatval($threshold) !== $threshold || $threshold < 0 || $threshold > 1 )
+				throw new \Error('Invalid threshold for Genome mutation.');
+
+			/* (2) Calculates how many neurons/synapses to mutate */
+			$neuronsMutations  = round( (count($this->neurons)  - 1) * $threshold );
+			$synapsesMutations = round( (count($this->synapses) - 1) * $threshold );
+
+			/* (3) Choose random neurons' indexes */
+			$iNeurons = [];
+			while( count($iNeurons) < $neuronsMutations ){
+				$r = rand(0, count($this->neurons)-1);
+
+				if( !in_array($r, $iNeurons) )
+					$iNeurons[] = $r;
+			}
+
+			/* (4) Choose random synapses' indexes */
+			$iSynapses = [];
+			while( count($iSynapses) < $synapsesMutations ){
+				$r = rand(0, count($this->synapses)-1);
+
+				if( !in_array($r, $iSynapses) )
+					$iSynapses[] = $r;
+			}
+
+			/* (5) Update chosen neurons */
+			for( $i = 0, $l = count($iNeurons) ; $i < $l ; $i++ )
+				$this->neurons[$iNeurons[$i]] = rand(self::MIN, self::MAX) / self::MAX;
+
+			/* (6) Update chosen synapses */
+			for( $i = 0, $l = count($iSynapses) ; $i < $l ; $i++ )
+				$this->synapses[$iSynapses[$i]] = rand(self::MIN, self::MAX) / self::MAX;
+		}
 	}
 
 
diff --git a/public/main.php b/public/main.php
index adfe229..4e831f8 100644
--- a/public/main.php
+++ b/public/main.php
@@ -58,11 +58,10 @@
 		echo implode(' ; ', $b->synapses)."\n\n";
 
 		/* (3) Section Title */
-		// $b->mutation(0.3); // @b has now mutated with a threshold of 30%
-		$b = new Genome(2, 3); // 2 layers of 3 neurons each -> randomly filled
-		echo "B neurons\n";
+		$b->mutation(0.3); // @b has now mutated with a threshold of 30%
+		echo "mutated clone neurons\n";
 		echo implode(' ; ', $b->neurons)."\n";
-		echo "B synapses\n";
+		echo "mutated clone synapses\n";
 		echo implode(' ; ', $b->synapses)."\n\n";
 
 		/* (4) Cross-over (father+mother) */